Depinning transition of bubble phases in a high Landau level

Abstract

In the higher Landau levels (N>0) a reentrant integer quantum Hall effect (RIQHE) state, which resides at fractional filling factors but exhibiting integer Hall plateaus, has been previously observed and studied extensively. The nonlinear dynamics of RIQHE were measured by microwave resonance, with the results consistent with an electronic bubble phase pinned by impurities. We have carried out Introduction In condensed matter systems nonlinear dynamics are commonly associated with a class of translational-symmetry-broken phases, often termed electronic crystals. Archetypical examples include Wigner crystals (WC), striped phase in high T c superconductors, charge order in organic materials, and charged colloidal crystals. Among these, nonlinear transport of the charge density wave (CDW) has been studied extensively [1,2], where CDW is pinned by impurities in a small bias regime. Its dynamics can be revealed by dramatic transport behaviors, such as threshold electric field (E T ) and conductance steps resulting from the de-pinning transition in an increasing bias. In the quantum Hall system which is realized in a two-dimensional electron gas (2DEG) under an intensive magnetic field, the WC, striped, and bubble phases have been observed [3][4][5][6][7][8][9][10][11][12][13]. In order to understand the nonlinear dynamics of these phases, it is of great interest to directly measure their critical transport parameters, such as thresholds for the de-pinning. However, such information is often obscured by off-diagonal component of the conductance tensor under magnetic fields.

Electron-solid and electron-liquid phases in graphene

“…Additionally, in higher Landau levels an effective short-range attractive interaction favors the formation of electron stripes or electron-bubble solids with two, three or more electrons per site [15][16][17][18][19][20][21][22][23][24] . A competition between the Wigner crystal (WC), electronic-bubble, and the quantum-liquid phase gives rise to a reentrant IQHE [25][26][27][28][29][30][31] . This effect consists of a series of first-order quantum phase transitions, much like the classical phase transition from ice to water, which occurs upon increasing the temperature.…”

Competing Fractional Quantum Hall and Electron Solid Phases in Graphene

“…This is characterized by the emergence of vanishing longitudinal resistance at fractional filling between the usual sequence of FQHE states, but with Hall conductivity restored to the closest integer value. Numerous experimental [10,14,[24][25][26] and theoretical studies [11,12,27] favor a collective origin for the RIQHE where the emergent electron solid is pinned by the underlying impurity potential. However, many of the experimentally reported details, such as the relative energy scales between different RIQHE states and apparent particle-hole asymmetry within a LL [14,25] remain poorly understood.The universality of the integer and fractional QHE found in a wide variety of high mobility 2D electron systems suggests that the formation of the electron solid should be equally ubiquitous.…”

Exploring Quantum Hall Physics at Ultra-Low Temperatures and at High Pressures

“…The above transport signatures of RIQHSs indicate a pinned insulator and the reentrant property was argued to distinguish RIQHSs from an Anderson insulator. 45,196 Following the discovery of RIQHSs, efforts on these states were focused on establishing their fundamental signatures in magnetotransport, on their filling factors of formation, 45,95,97,197 on gaining an understanding of their energy scale, 95,197 on their microwave pinning modes, [198][199][200] on thermopower, 201 on their electrical breakdown, 196,[202][203][204][205][206] and most recently, on their attenuation of surface acoustic waves. 207,208 RIQHSs develop at temperatures higher than 100 mK in the third Landau level and at tens of mK in the second Landau level.…”